Sonic treating apparatus



30, J w MCAULEY SONIC TREATING APPARATUS 4 Sheets-Sheet 1 Original FiledMarch 18, 1957 M 4 lax/ 7 ATTORNEYS July 30, 1963 J. w. MCAULEY SONICTREATING APPARATUS 4 Sheets-Sheet 2 Original Filed March 18, 1957 H WWWl IIIIHIIII nmmmfi iiiiiiiiiii INVENTOR. g'd/nwL WWP BY $656 ATTORNEYSJuly 30, 1963 J. w. MCAULEY SONIC TREATING APPARATUS 4 Sheets-Sheet f5Omginal Filed March 18, 1957 INVENTm. BY gm; Wf @l/z? 2066c fi dwvpeATTORNEYS July 30, 1963 J. w. M AuLE 3,099,759

SONIC TREATING APPARATUS Original Filed March 18, 1957 4 Sheets-Sheet 419 INVENTOR.

A TTORNE Y5 United States Patent Original application Mar. 18, 1957,Ser. No. 646,691. Divided and this application May 4, 1959, Ser. No.

Claims. (Cl. 31ll26) The present invention relates broadly to sonicvibration genera-ting apparatus, and more particularly to an improvedform of surface treating apparatus that employs sonic vibrations.

This application is a division of application Serial No. 646,691, filedMarch '18, 1957, now abandoned.

Although the invention is by no means restricted thereto, it has beenfound to be especially well adapted to carry out the diflicult job ofremoving heat hardened plaster of Paris from the iiat tops of metaltables employed in the surfacing of plate glass and it will be describedin that connection here.

During the conventional commercial production of ground and polishedplate glass, unfinished plate glass blanks are normally secured to thetops of the grinding and polishing tables by bedding the blanks in alayer of plaster of Paris in order to hold them in place during thesurfacing treatment. After the exposed surface of the glass has beenground and polished the blank is removed from the tables and it is thennecessary to remove the old plaster and apply a fresh layer forreceiving subsequent blanks.

Because of the extremely tight bond between the plaster of Paris and thetables after the plaster has set up and been subjected to the grindingand polishing heat, removal of the old plaster presents a seriousproblem in plate glass plants. Heretofore, cleaning of the tables hasbeen accomplished by rotary wire brushes acting in conjunction w-ithwater under pressure. However, the abrading action of the Wire damagesthe table tops and causes them to erode, thus requiring the tables to bemore frequently resurfaces and replaced. Also the large amounts of waternecessary to such a cleaning process makes the cleaning area damp,dangerous and unsightly; and the necessity of frequent adjustment of thebrushes as they wear down, and replacement when they become too worn foreffective use makes for increased maintenance costs.

Now, however, by means of the present invention, even this difiicult andunusual cleaning job can be carried out Without the deficiencies andobjectionable features of the previous cleaning method by the use ofsonic vibration, preferably in frequencies between 100 and 30,000 cyclesper second, which are transmitted in the form of vibration sound wavesthrough a suitable medium against the surface to be cleaned. As thesound waves are propagated through the medium, which is preferably aliquid for our purposes, motion of the particles of liquid is related tol the characteristics of the sound waves. That is, the sound waves willproduce an alternate formation and collapse of gas bubbles or cavities,which phenomenon is referred to as cavitation. The collapsing of thebubbles or cavities creates an agitation within the medium of sulficientmagnitude to disintegrate particles of substantially solid materialwhich are in contact with the medium.

It has become general practice to produce high frequency sound energy bymeans of vibratory devices whose operation depends on the phenomenon ofmagnetostriction.

However, transducers of the magnetostrictive vibratory type heretoforeused for cleaning purposes had a number of disadvantages. Among thesewere frequent short circuits in the energizing coils, eihciency reducingvibration 3,099,759 Patented July 30, 1963 "ice frequency shifts due toexcessive heating of the transducers, broken mountings resulting fromthe sound vibrations, and transducer erosion caused by cavitation.

The apparatus of the present invention is designed to overcome thesedisadvantages and it is accordingly an important object of the inventionto provide vibratory device with improved means for insulating theenergizing coils.

Another object is to provide a cooling means for maintaining theoperating temperature of the vibratory device below a predeterminedmaximum allowable value.

Still another object is to provide a mounting for the vibrationgenerating device that is capable of withstanding the sound energyforce.

A still further object is to provide a vibratory device in whichportions contacting the energy transmitting medium are constructed of aneasily replaceable erosion resistant material.

Still another object is the provision of a vibratory device including animproved laminated core.

Other objects and advantages of the invention will become more apparentduring the course of the following description when taken in connectionwith the accompanying drawings.

In the drawings wherein like numerals are employed to designate likepar-ts throughout the same:

FIG. 1 is a perspective view of a portion of a grinding and polishingline, showing a cleaning apparatus constructed in accordance with theinvention incorporated therein;

FIG. 2 is a fragmentary perspective view on an enlarged scale, of aportion of the cleaning apparatus of FIG. 1, and showing two cleaningmodules;

FIG. 3 is a longitudinal section taken substantially along the line 33of FIG. 2;

FIG. 4 is an end view of one of the modules;

FIG. 5 is a fragmentary vertical, transverse, cross-sectional view takenalong line 5-5 of FIG. 3,. and showing one of the transducers aspositioned in the cleaning module;

FIG. 6 is a horizontal cross-sectional view of a transducer horn, takenalong line 6-6 of FIG. 4;

FIG. 7 is a horizontal cross-sectional view of a transducer horn takenalong line 7-7 of FIG. 4;

FIG. 8 is a fragmentary view of a portion of the transducer horn showinga wear plate attached;

FIG. 9 is a perspective view of an improved insulated energizing coilaccording to the invention;

FIG. 10 is a detail view partially in section of a moditfied form oftransducer hor-n;

FIG. 11 is a perspective view of a module with a modified cover; and

FIG. 12 is an end view partially in section of two modules and amodified cooling means.

With more detailed reference now to the drawings, and particularly toFIG. 1, there is shown the plaster cleaning zone of a grinding andpolishing line made up of a series of tables 10 for carrying glasssheets from a loading zone along an endless predetermined path, firstbeneath a series of grinding unit, then beneath a number of polishingunits, to an unloading zone, and finally along a return section to theloading zone again.

As was stated above, the first step in surfacing glass sheets is tosecune them to the tops of the tables 10 by bedding the sheets in arelatively thin layer of plaster. This is preferably done in the loadingzone. After the upper faces of the glass sheets have been surfaced underthe grinders and olishers and the sheets removed from the tables in theunloading zone it then becomes necessary to remove and clean the oldhardened plaster 11 from the table tops before the tables may he usedagain for another surfacing operation. The plaster is usually -13removed from the table in a table cleaning zone located between theunloading zone and the loading zone and as generally shown in FIG. 1.

The apparatus that is designed to remove the layer of old plasteraccording to this invention includes a plurality of transducers orvibration generating elements 12 including'a vibration source andamplifier or acoustical horn 1-3. These vibration generating elementsare preferably-arranged in units or modules 14 mounted in a uniquefashion, on a supporting means shown generally at 15, above andtransversely of the surfacing tables iii.

In order to clean the table surfaces by sonic methods a layer of liquidor other suitable vibration transmitting material 16 is supplied andmaintained between and in contact with the sheets to be cleaned and theworking faces of the horns 13 from a nozzle .17. The purpose of thistransmitting material is to provide a medium in which the sonicvibrations may produce cavitation which will agitate the mediumsufliciently to loosen foreign particles from the surface of the tablesand permit these particles to be easily removed. This loosening of theforeign particles and their subsequent removal provides the desiredcleaning function.

In a preferred embodiment the transducers 12 are mounted in groups ofsix, which groups or modules 14 are of a unitary nature permitting theirready placement in operating position or removal and replacement in caseof malfunctioning. These modules rest on horizontal angle irons 18 and19, positioned above and transversely of the tables on supportstructures 20 at opposite sides of the line. The vertical height of thesupport means 15 is such as to provide a space between the surface to becleaned and the work surface of the horns of .060 to .100 inch. As isshown in FIG. 1, a plurality of the modules are arranged in two lineswith the modules in each line arranged in an abutting relationship andthe two lines slightly staggered with respect to one another so thatthey will sweep the complete width of the tables 10 and not leave anyunoleaned strips such as, for example, would be formed between twomodules if only one line were used.

In order to overcome the high amount of heat that is produced by thetransducers during their operation, cooling air under pressure isbrought through a conduit 21, supply tubes 22, hoods 23 which fittightly over the top of module covers 23', and then down over thetransducers. The cooling air not only serves to increase the operatinglife of the transducers but also prevents unwanted frequency shiftswhich are brought about by excessively high temperatures in atransducer.

Each module is carried by a mounting bracket '24 comprising a pair ofend plates 25 to which are affixed two longitudinal angle irons 26.These irons 26 are spaced parallel to one another and with enough spacebetween them to permit the horns of the transducers to fit into this.space, while the length of these irons 26 is sufficient to accommodatesix transducer widths. The upper surface of each of the irons 26 areprovided with six equally spaced pin-like projections 27. Theseprojections are received by the positioning slots 28 in the mountingflanges 29 of the transducers and are used for positioning theindividual transducers in their proper relationship in a module as shownin FIG. 3.

When a module is being built up the individual transducers are placedonto the mounting irons 26 as shown in FIG. 3 with their horns extendingdownwardly through the space between the plates and the position slots28 of the transducers engaged with the appropriate mounting pinsorprojections 27. After the transducers have been so placed on irons 26two securing bars 30 are then placed down over the mounting flanges 29and are secured to the mounting irons by means of bolts 31 which whentightened maintain the transducers in a fixed contacting relationshipwith the mounting irons 26. These securing bars 30 replace the formermethod which was to bolt each of the transducers to the mounting irons26. This older method was not satisfactory because the vibration of thetransducers was sufiicient to break off the heads of the bolts and as aconsequence necessitate repair or replacement. However, with theimproved method of securing described herein six of the transducers aresecured by means of two bars 30 which are themselves secured by fourbolts of such size as to preclude their being broken during operation.

As seen best in RIG. 5, the transducers which generate the sonic energyused in the cleaning process in a U- shaped core or transducer stack 32of very thin laminated nickel leaves or strips; a coil 33 arranged insurrounding relation to the legs of the U-shaped core and which whenconnected to an appropriate alternating power source will set up analternating held within the core; a magnet 34 positioned between thelegs 32' of the core and above the coil to provide a polarizing effecton the core; and an acoustical horn 13 which is secured firmly to thecross leg of the core for directing the vibratory energy produced by themagnetostrictive movement of the core to a region where this energy maybe utilized.

Briefly, the principle of operation of the transducer is that analternating field is set up in the core 32 when an alternating currentis flowing in coil 33 which because of the ferromagnetic properties ofthe core produces a cyclic increase and decrease of the core length oftwice the frequency of the voltage which is energizing the coil. Sincethe acoustical horn 13 which is firmly affixed to one end of the coremoves with each cyclic changing length of the core the free end of thehorn acts as a useful source of vibratory energy. The frequency of thevoltage used is preferably 10 kilocycles although a number ofsatisfactory values may be found from cycles to 30 kilocycles dependingon the type of cleaning operation performed, the amount of power used,and the design of the transducers.

As is shown particularly in FIGS. 3 and 4, the core 32 is constructed ofa plurality of thin U-shaped strips of metal which are stacked togetherto form a unitary structure. These laminations are made of aferromagnetic material such as nickel which are provided with an oxidecoating to insulate them from one another to reduce heat produced byeddy currents. Heretofore, iaminations of approximately .010 of an inchthickness were used for such purpose, but it was found that by reducingthis to around .007 of an inch eddy current losses can be reduced by 50%and notably better results obtained.

Heretofore the horns used in cleaning apparatus of the general typebeing discussed here required frequent replacement and it was determinedthat this was because the horns were so fashioned as to have recesses orconicavities exposed to the action of cavitation erosion. This inventionutilizes a specially shaped energy directive member .13 (best shown inFIGS. 5, 6 and 7) which comprises an elongated hollow body of polygonalcross section including side walls 37 and an outer end wall 38 whichenclose a cavity 35. This cavity as shown in FIGS. 5 and 7 has acircular cross section when viewed along the path that the sonic energyis to travel. When the cavity i viewed at right angles to the path ofsonic transmission the lower portion as in :FIG. 5 shown slightlydiverging walls as they are viewed moving away from the core piece 32,whereas the portion 36 closer to the core piece is an exponential curve.Thus, the cavity is constructed of a cone portion generated by revolvingan exponential curve about a reference axis. Not only do the relativelysmooth outer surfaces of the side walls 37 of the horn preclude severeerosion possibilities, but the use of the particularly shaped cavitywithin the horn provides an amplification of sonic energy. Therefore,because of this cavity sonic energy supplied at the upper end of thehorn by the core will be amplified by the horn effect and present sonicenergy of greater amplitude to the transmitting medium.

One satisfactory method of producing a born as described above is tocast it in two pieces and then weld the two pieces together into thefinal horn. It has been found that the configuration of the line of weldof the two pieces is very important in determining the ability of thisweld to withstand deterioration by the sonic energy. For example, in thepreferred embodiment a vertical weld a, that is one which is alignedwith the direction of transmission of sonic energy, is found to bepractically unaffected by the transmission of sonic energy therethrough.Whereas a line of weld which is substantially at right angles to thedirection of transmission of the sonic energy is found to be veryquickly weakened and destroyed.

The outer end wall 38' of the horn 13 is the portion which is placed incontact with the energy transmitting medium during a cleaning operationand is the portion which is subjected to the greatest amount of erosivewear by cavitation which wear at this point was a frequent cause ofreplacement of prior known transducers. The present invention overcomesthis limitation by providing a wear-plate 39 (see FIG. 8) of hardenednon-corrosive steel which is secured to the outer working face of theend wall 3 8 of the horn which is normally brought into contact with theenergy transmitting medium. One satisfactory method of affixing thiswear-plate to the transducer horn is by the use of an epoxy cement whichis shown in FIG. 8 as a thin layer 40.

In FIG. 10 there is illustrated an acceptable form of weld configurationwhich also has been found to provide a satisfactory horn.

In order to overcome previously encountered difficulties with electricalshort circuits between the different layers of wires in the energizingcoil 33 and between the coils and the core 32 of the transducer thesecoils in the present invention have been impregnated with a highlyinsulative plastic material.

In fact, the coil assembly 41, as illustrated in FIG. 9, is completelyembedded in a plastic body. This assembly consists of two sets of coils33 each of which is wound in such a manner so as to encircle anelongated opening 42. When these coils are embedded in the plastic theopenings are slightly wedge-shaped. The dimensions of the openings aresuiiicient to enable them to accommodate six core pieces. Thus, when thetransducers have been mounted in position in a module, 'as describedhereinabove, the coil assembly is then lowered down onto the core piecesso that the openings 42 will receive the core pieces. When in finalassembled position each of the coils 33 encircles one half of the legsof the core pieces. The magnets 34 are then placed in position betweenthe core legs as is shown particularly in FIGS. 4 and 5 and heldsecurely in place by retaining strip 34 attached to the inner surface ofthe module cover 23'.

Electrical power is applied to these coils through cable 43 which is ofconventional structure. The plastic material protects the coil wiresfrom the absorption of moisture and from the incurring of any damage tothe coils when they are placed in position on the legs 32' of the core.This moisture-resistant feature is especially necessary when thetransducers are cooled by water.

As was discussed previously herein the transducers produce a largeamount of heat during operation and as a consequence of their elevatedtemperature they show a tendency to vary the frequency of the generatedsonic energy. Therefore, as was also described herein, applicant hasprovided means for cooling the transducer by forced air means. Amodified cooling means shown in FIGS. 11 and 12 is that of using waterto reduce the temperature of the vibratory energy generating device. inorder to be able to do this the outside case 44 of each module in thismodification is constructed of a foraminous material which will permitthe application of sprays or 6 streams 45 of cooling water to thetransducers. These sprays may be supplied by any of a number ofdifferent conventional nozzles 46.

Although the present invention has been particularly described inconnection with the removal of plaster from grinding and polishingtables, it has also been found to possess utility in the cleaning ofsheet materials, such as fior example glass sheets.

We claim:

1. In sonic energy generating apparatus comprising a plurality ofmagnetostrictive transducers arranged in sidebyeside relation, eachtransducer including a core, polarizing means and a metallic acousticaldirective member secured to the core and extending therefrom insubstantial alignment with the major direction of magnetostrictivemovement of the core, a member having high insulation propertiesprovided with an elongated opening for removably receiving the cores ofthe transducers therein when said transducers are in said side-by-sidearrangement, and an inductively wound coil of wire embedded in saidmember encircling the cores of the several transducers.

2. In sonic energy generating apparatus as claimed in claim 1, in whicheach core comprises spaced legs and in which said member is providedwith spaced elongated openings for loosely receiving the spaced legs ofthe transducer cores therein.

3. In sonic energy generating apparatus as claimed in claim 1, in whichsaid opening is tapered in the direction of the cores, wit-h the largerend of the opening being adjacent the directive member.

4. A magnetostrictive transducer for imparting vibratory energy to atransmitting medium, comprising a core formed of insulated nickel sheetsof a thickness less than .007 of an inch, an inductively wound coil ofwire encircling said core, a core polarizing means, and a metallicacoustical directive member fixedly secured to the core and extendingtherefrom in substantial alignment with the major direction ofmagnetostrictive movement of the core.

5. In vibratory energy generating apparatus comprising a sonic energygenerating module composed of a plurality of magnetostrictivetransducers provided with notched flanges, a supporting surface providedwith a plurality of uniformly spaced positioning pins received in saidnotches to hold the transducers in uniformly spaced relation, andsecuring means engaging said flanges for fixedly maintaining thetransducers in said spaced relation.

6. In vibratory energy generating apparatus of the type comprising asonic energy generating module consisting of a plurality of transducersarranged side by side and each having a substantially Uashaped core,with the legs of the cores arranged in two lines substantially parallelto one another, a unitary coil assembly consisting of a pair of Wirecoils, one coil encircling one line of legs of the several transducersand the other coil encircling the other line of legs, and a plasticmember in which said unitary coil assembly is embedded and which isremovably received on said cores.

7. -A magnetostrictive transducer for imparting vibratory energy to atransmitting medium, comprising a core of magnetostrictive material, aninductively wound coil of wire encircling said core, a core polarizingmeans, a metallic acoustical directive member secured and extendingoutwardly from said core in substantial alignment with the direction ofmajor magnetostrictive movement of the core, a metal wear plate disposedover the outer end of said acoustical directive member, and a layer ofan epoxy cement interposed between said wear plate and the outer end ofsaid acoustical directive member and securing them to one another.

8. In vibratory energy generating apparatus of the type comprising asonic energy generating module including a plurality of transducersarranged side-by-side and each having a substantially Usshaped core,with the legs of the cores of said transducers being arranged in twolines subsmamial-ly parallel to one another, 'and a unitary coi lassembly comprising a plastic member having a pair of spaced pamalllelelongated :slodzs for loosely receiving themthnoulgh fiche spaced linesof legs of the cores and a pair of coils embedded in said plasticmember, one coil encircling one line of legs and the second ooilencircling the ofnher line of Legs.

9. In vibratory energy generating appanatus as claimed in claim 8, inwhich said elongated xslo t-s are tapered in the direction of nhe cores,with the larger end of each slot being adjacent (the inner ends of saidcores.

l0. In vibratory energy generating apparatus as claimed 111011311118,including a polarized magnet received between the legs of each core forretaining the plastic member in position.

References Cited in the file of this patent UNITED STATES PATENTS 82,632,858 Ca'losi Mar. 24, 1953 2,651,148 Carwile Sept. 8, 19532,704,333 Oalo'si et a1 Mar. 15, 1955 2,717,319 Bandy Sept. 6, 19552,745,084 Bundy May 8, 1956 2,748,298 Calosi et a1 May 29', 19562,784,119 McCrown et a1. Mar. 5, 1957 2,883,310 McAuley Apr. 21, 19592,930,913 Camp et Ial Mar. 29, 1960 2,946,981 'ONeflll July 26, 19602,964,837 Harris Dec. 20, 1960 FOREIGN PATENTS 844,160 France Mar. 23,1938 OTHER REFERENCES Electrical Engineers Handbook, Fender-Del Mar, 4thedition, Electric Power, pages 3-22, see. 24.

1. IN SONIC ENERGY GENERATING APPARATUS COMPRISING A PLURALITY OFMAGNETOSTRICTIVE TRANSDUCERS ARRANGED IN SIDEBY-SIDE RELATION, EACHTRANSDUCER INCLUDING A CORE, POLARIZING MEANS AND A METALLIC ACOSTICALDIRECTIVE MEMBER SECURED TO THE CORE AND EXTENDING THEREFROM INSUBSTANTIAL ALIGNMENT WITH THE MAJOR DIRECTION OF MAGNETOSTRICTIVEMOVEMENT OF THE CORE, A MEMBER HAVING HIGH INSULATION